Fatty acid esters of hydroxyalkanesulfonic acid amine salts



FATTY ACID ESTERS OF HY DROXYALKANESUL- FONIC ACID AMINE SALTS Arthur R. Sexton and Edgar C. Britten, Midland, Mich, assignors to The Dow Chemical Company, Midland, M1ch., a corporation of Delaware No Drawing. Filed Mar. 3, 1958, Ser. No. 718,412

17 Claims. (Cl. 260-401) This invention relates to new compositions of matter and particularly to fatty acid esters of vic-hydroxyalkanesulfonic acid amine salts representable by the conventional formula wherein the group RCO corresponds to an aliphatic carboxylic acid RCO H having from eight to twenty carbon atoms, the symbol R' represents a vicinal bivalent alkylene radical having from two to four carbon atoms, and the symbol HAm represents an ammonium cation corresponding to a primary, secondary, or tertiary amine having alkyl, cycloalkyl, aralkyl, hydroxyalkyl, or aminoalkyl substitutents in which the total number of carbon atoms is from one to twenty.

Examples of the new fatty acid esters of hydroxyalkanesulfonic acid amine salts include ones which are esters of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, ones wherein the alkylene radical corresponds to the ethylene, propylene, and butylene radicals, and ones in which the sulfonic acid salt is that of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, the isopropanolamines, cyclohexylamine, dicyclohexylamine, benzylamine, and ethylenediamine.

Specific examples of such fatty acid esters of hydroxyalkanesulfonic. acid amine salts and their conventional formulae are as follows:

Triethylamine salt of 2-sulfoethyl caprylate:

Those skilled in the art will be able to perceive other specific examples of fatty acid esters of hydroxyalkanesulfonic acid amine salts from the disclosure in the preceding paragraph of specific carboxylic acids, specificalkylene radicals corresponding to the hydroxyalkanesultonic acids, and specific amines. Mixtures of fatty acid esters of hydroxyalkanesulfonic acid amine salts are also contemplated, for example, the mixtures correspondingto represents an olefin oxide such as ethylene oxide, 1,2- propylene. oxide, 1,2-butylene oxide, 2,3-butylene oxide, or isobutylene oxide and wherein HSO HAm represents States Patent mixed fatty acids, mixed hydroxyalkanesulfonic acids, and or mixed amines.

While the alkali metal, e.g. sodium, salts of some fatty acid esters of hydroxyalkanesulfonic acids are already known, the present amine salts of fatty acid esters of hydroxyalkanesulfonic acids are new and advantageous over the alkali metal salts.

The new fatty acid esters of hydroxyalkanesulfonic acid amine salts can be prepared by esterification reaction between a fatty acid halide such as a fatty acid chloride and a vic-hydroxyalkanesulfonic acid amine salt, such reaction being representable by the equation:

wherein the symbol X represents a halogen such as chlorine or bromine and the other symbols have meanings hereinbefore given, provided the reaction is carried out in the manner fully set forth below.

The vichydroxyalkarresulfonic acid amine salts employed as starting material in this reaction can be obtained by interaction of an alkylene epoxide and an aqueous amine bisulfite in accordance with the equation:

0 wherein represents an olefin oxide such as ethylen oxide, 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, or isobutylene oxide and wherein HSO HAm represents an amine bisulfite salt. This method of making amine salts of vic-hydroxyalkanesulfonic acids is fully set forth in copending application of Arthur R. Sexton, Serial No. 670,381, filed July 8, 1957, and comprises mixing and reacting an olefin oxide with an amine bisulfite salt in an aqueous medium having a pH value of not less than 4 until the bisulfite salt is substantially consumed. The amine salts can also be made by stoichiometric reaction of the basic amine and a vic-hydroxyalkanesulfonic acid.

Itis contemplated that mixed vic-hydroxyalkanesulfonic acid amine salts be prepared from mixtures of olefin oxides and/or from mixtures of amines and that such mixed vic-hydroxyalkanesulfonic acid amine salts be subsequently reacted with a fatty acid halide or mixture of fatty acid halides. The term hydroxyalkanesulfonic acid is used herein to mean a vic-hydroxyalkanesulfonic acid.

The preparation of the new fatty esters of hydroxyalkanesulfonic acid amine salts by reaction of a fatty acid halide with a hydroxyalkanesulfonic acid amine salt' is preferably carried out by heating a mixture of the fatty acid halide and the hydroxyalkanesulfonic acid amine salt starting materials at a temperature of from 70 to C. under a reduced pressure of not more than 200 mm. of mercury, absolute pressure, preferably while subjecting the reaction mixture to mechanical working, while removing the evolved hydrogen halide from the reaction zone as swiftly and thoroughly as possible.

The starting materials are employed in amounts corresponding to an equivalent or slight excess of the amine salt of the hydroxyalkanesulfonic acid relative to the fatty acid halide in order to insure complete consumption of the'latter. Usually, the fatty acid halide is added to the hydroxyalkanesulfonic acid salt under reaction conditions at rates corresponding to the rate of consumption of the acyl halide by the ester-forming reaction.

When a substantially theoretical amount of hydrogen halide has been evolved from the reaction mixture, the reactionis regarded as complete, and the resulting product is essentially the fatty acid ester of the hydroxyalkanesulfonic acid amine salt.

It is noteworthy that these results have not been obtained when these starting materials, i.e. a fatty acid halide and a hydroxyalkanesulfonic acid amine salt, are heated together at atmospheric pressure; under such conditions, an amine hydrochloride is produced and the desired fatty acid ester of the hydroxyalkanesulfonic acid amine salt is not obtained.

Since the reaction product as described above is essentially the fatty acid ester of the hydroxyalkanesulfonic acid amine salt, it can be used as such for many purposes. If necessary or desirable, it can be further purified by crystallization and/or extraction with selective solvents.

The new fatty acid esters of hydroxyalkanesulfonic acid amine salts are advantageously useful as, and in the preparation of, liquid detergents, textile scrubbing aids, surfactants, and wetting agents in aqueous and nonaqueous compositions. When used as laundry detergents, the new fatty acid esters of hydroxyalkanesulfonic acid amine salts are less irritating to the skin and less injurious to delicate fabrics than are the harsh alkali detergents.

The following examples illustrate the invention but are not to be construed as limiting its scope.

Example 1.-Preparation of triethanolamine salt of 2- sulfoethyl ester of coconut oil fatty acids A charge of 534 grams of the triethanolamine salt of isethionic acid was placed in a sigma-blade mixer. The salt was previously obtained by reaction of ethylene oxide on triethanolamine bisulfite salt in water solution and recovery of the resulting triethanolamine salt of isethionic acid. The salt was heated to temperatures in the range of from 110 to 115 C. under 200 mm. of mercury, absolute pressure, while 410 grams of the acyl chlorides corresponding to the fatty acids of coconut oil was added dropwise over a period of 0.5 hour. Heating was continued for an additional hours while the pressure was progressively reduced to 20 mm. of mercury absolute. During these operations, the reaction mass was intensively mixed and kneaded while hydrogen chloride was evolved and was withdrawn from the reaction zone to a caustic trap until an amount of hydrogen chloride theoretically corresponding to the acyl chloride charged had been collected. The resulting reaction product was cooled and removed from the mixer-reactor as a thick paste. The triethanolamine salt of 2-sulfoethyl ester of coconut oil fatty acids thereby produced amounted to 880 grams. Its solubility properties are shown in Table 1.

Example 2.Preparatin of triethylamine salt of 2- salfoethyl caprylate The procedure described above in Example 1 was substantially repeated using as starting materials approximately stoichiometric quantities of the triethylamine salt of isethionic acid and capryloyl chloride. The triethylamine salt of isethionic acid was previously obtained by reaction of ethylene oxide with triethylamine bisulfite in an aqueous reaction mixture and recovery of the resulting triethylarnine salt of isethionic acid.

The resulting triethylamine salt of 2-sulfoethyl caprylate was a thick syrup, yield about 95 percent of theoretical. Its solubility characteristics are shown in Table 1.

Example 3.-Preparation of cyclohexylamine salt of xsulfo-x-butyl laarate The procedure described above in Example 1 was substantially repeated using as starting materials approximately stoichiometric quantities of the cyclohexylamine salt of x-hydroxy-x-butanesulfonic acid and lauroyl chloride. The cyclohexylamine salt of the hydroxybutanesulfonic acid was obtained by reaction of butylene-oxide and cyclohexylaminebisulfite in aqueous solution. The

butylene oxide was a mixture of the isomeric normal butylene oxides (approximately 94 percent 1,2-butylene oxide and 6 percent 2,3-butylene oxide) and gave rise to a mixture of the corresponding isomeric vicinalhydroxybutanesulfonic acids as cyclohexylamine salts. This salt mixture was recovered and reacted with lauroyl chloride to produce a quantitative yield of the cyclohexylamine salts of the isomeric vic-sulfobutyl laurates as a syrup whose solubility characterististics are shown in Table 1.

Example 4.-Preparazion of cyclohexylamine salt of x-' sulfo-x-propyl oleate Example 5.Preparation of triethylamine salt of 2- salfoethyl stearate The procedure described in Example 1 was substanstantially repeated using as starting materials approximately stoichiometric quantities of the tirethylamine salt of isethionic acid (preparation described in Example 2) and stearoyl chloride. The triethylamine salt of 2-sulfoethyl stearate was obtained as a pale yellow wax in approximately quantitative yield. Its solubility characteristics are shown in Table 1.

In like manner, the triethylamine salt of 2-sulfoethyl palmitate is prepared by heating a mixture of triethylamine salt of isethionic acid and palmitoyl chloride under reduced pressure until the evolution of hydrogen chloride is complete.

Example 6.-Preparati0n of benzylamine salt of xsulfo-x-propyl laurate The procedure described in Example 1 was substantially repeated using as starting materials approximately stoichiometric quantities of lauroyl chloride and a mixture of the benzylamine salts of l-hydroxy-Z-propanesulfonic acid and Z-hydroxy-l-propanesulfonic acid obtained by reaction of propylene oxide on an aqueous solution of benzylamine bisulfite. The resulting reaction product was a soap-like solid in approximately quantitative yield. Itssolubility characteristics are shown in Table 1.

In similar manner, other fatty acid esters of hydroxyalkanesulfonic acid amine salts can be made by employing other of the fatty acid halides and other vicinal hydroxyalkane-sulfonic acid amine salt as hereinbefore described. i

TABLE 1.SOLUBILITY CHARACTERISTICS OF FATTY ACID ESTERS OF HYDROXYALKANESULFONIO ACID AMINE SALT PRODUCTS OF THE EXAMPLES petroleum ether. .4

.5 The new fatty acid esters of hydroxyalkanesulfonic acid amine salts are surface-active agents, advantageously useful as, or in the preparation of, liquid detergents, laundry preparations, textile scrubbing aids, and the like. The surface active properties of some of these fatty acid esters of hydroxyalkanesulfonic acid amine salts are set forth in Table 2. All of these tests were carried out on solutions in de-ionized water containing 0.1 percent by weight of the test materials.

6 Example 7 To clean water having a hardness of 150 ;p.p.m. are added 0.75 gram of sodium 'tripolyphosphate and 0.4 gram of the cyclohexylamine salt of x-sulfo-x-butyl iaurate (from Example 3) per liter of water. The 'water solution is maintained at 120 F., and standard soiled cotton cloth is agitated therein with washing machine action for TABLE 2 Foam Height, mm. Inter- Test From 1. Wetting facial No. Material Example time, Tension,

1 No.- Instant After Minutes dynesl Minutes cm.

1 2-sulfoethyl stearate, triethylamine salt 5 20 2. 4 9. 2 2 :r-sulfo-propyl laurate, benzylamine salt. 6 180 180 0. 13 3. 8 3 x-sulio-r-butyl laurate, cyclohexylamine sal 3 179 179 0.10 4. 0 4 :t-sulfo z-propyl ole-ate, cyclohexylamine salt 4 132 132 0. 43 i. 4 5 2-sulioethyl laurate, sodium salt 82 82 0. 18 12. 1 6 2sulfoethy1 ester of coconut oil fatty acids,

sodium salt 117 117 0. 39 6. 9 7 z-sulfo-x propyi laurate, sodium salt 60 48 0. 08 10.0

For purposes of contrast with the new amine salts, data are also shown in Table 2 for several sodium salts of fatty acid esters of hydroxyalkanesulfonic acids.

The data reported in Table 2 under the heading Foam Height were obtained on test solutions containing 0.1 percent by weight of the test compounds by means of the procedure described by J. Ross and G. D. Miles in Oil and Soap, 18, pp. 99-102 (1941), modified by using 100 m1. of the test solution at the bottom of the column.

The Wetting Time shown in Table 2 was determined by the procedure described by C. Z. Draves and R. G. Clarkson in American Dyestuif Reporter, 20, pp. 201-208 (1931), modified by employing a nine-inch length of fabric tape (Synthron tape made by U.S. Testing Service, Inc., Hoboken, New Jersey), a one-gram hook, and a forty-gram weight.

The Interfacial Tension values were measured with the duNouy Interfacial Tensiometer on the interface between the test aqueous solution and a refined mineral oil (see J. C. Harris, Detergency Evaluation and Testing, published 1954 by Interscience Publishers, Inc., New York).

From the data in Table 2, it can readily be seen that the fatty acid esters of hydroxyalkanesulfonic acid amine salts have the properties of excellent surfactants.

The amine salts are considerably more soluble in water than are the alkali metal, e.g. sodium, salts of the fatty acid esters of hydroxyalkancsulfonic acids. This water solubility permits the preparation of aqueous liquid compositions that are highly concentrated in the fatty acid esters of hydroxyalkanesulfonic acid amine salts.

Furthermore, the amine salts are quite soluble in nonaqueous polar liquids such as alcohol and in non-polar liquids such as benzene, toluene and the like, as shown in Table 3. In contrast, the alkali metal, e.g. sodium salts of these fatty acid esters of hydroxyalkanesulfonic acids are almost insoluble in such non-polar liquids and are only slightly soluble in non-aqueous polar liquids.

ten minutes. After rinsing and drying, the cloth is found to be substantially clean of soil.

In place of the cyclohexylamine salt of x-sulfo-x-butyl laurate in this example there can be employed another of the fatty acid esters of hydroxyalkanesulfonic acid amine salts previously described herein with substantially the same results.

Example 8 A two percent by weight solution of the benzylamine salt of x-sulfo-x-propyl laurate (from Example 6) in toluene is found to be an effective detergent for cleaning accumulated dirt and grease from used machine parts.

That which is claimed is:

1. A method of making fatty acid esters of hydroxyalkanesulfonic acid amine salts which comprises mixing approximately stoichiometric amounts of a fatty acid halide having from eight to twenty carbon atoms and a vic-hydroxyalkanesulfonic acid amine salt wherein the vic-hydroxyalkanesulfonic acid has from two to four carbon atoms and the amine has from one to twenty carbon atoms, by adding the fatty acid halide to the vic-hydroxyalkanesulfonic acid amine salt incrementally as required by the ensuing esterification reaction and heating the resulting mixture at temperatures of from 70 to C. under an absolute pressure not greater than 200 mm. of mercury while removing the evolved hydrogen halide as formed from the reaction mixture.

2. A method according to claim 1 wherein the fatty acid halide is the acyl chloride of coconut oil fatty acids.

3. A method according to claim 1 wherein the fatty acid halide is capryloyl chloride.

4. A method according to claim 1 wherein the fatty acid halide is lauroyl chloride.

5. A method according to claim 1 wherein the fatty acid halide is oleoyl chloride.

6. A method according to claim 1 wherein the fatty acid halide is stearoyl chloride.

7. A method according to claim 1 wherein the amine salt is the triethanolamine salt of isethionic acid.

8. A method according to claim 1 wherein the amine salt is the triethylamine salt of isethionic acid.

9. A method according to claim 1 wherein the amine salt is the cyclohexylamine salt of a vic-hydroxybutanesulfonic acid.

10. A method according to claim 1 wherein the amine salt is the cyclohexylamine salt of a vic-hydroxpropanesulfonic acid.

11. A method according to claim 1 wherein the amine salt is the benzylamine salt of a vic-hydroxypropanesulfonic acid.

12. A method according to claim 1 wherein the fatty acid halide is the acyl chloride of coconut oil fatty acids and the amine salt is'the triethanolamine salt of isethionic acid.

13. A method according to claim 1 wherein the fatty acid halide is capryloyl chloride and the amine salt is the triethylamine salt of isethionic acid.

14. A method according to claim 1 wherein the fatty acid halide is lauroyl chloride and the amine salt is the cyclohexylamine salt. of a vic-hydroxybutanesulfonic acid.

15. A method according to claim 1 wherein the fatty acid halide is oleoyl chloride and the amine salt is the cyclohexylamine salt of a vic-hydroxypropanesulfonic acid.

16. A method according to claim 1 wherein the fatty 1.7. A method according to claim 1 wherein the fatty acid halide is lauroyl chloride and the amine salt is the benzylamine salt of a vic-hydroxypropanesulfonic acid.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Hoyt: German Chemical Developments in Synthetic Detergents and Wetting Agents, Hobart Publishing Comacid halide is stearoyl chloride and the amine salt is the 15 pany, Inc., Box 4127, Chevy Chase Branch, Washington triethylamine salt of isethionic acid.

15, D.C., page 15.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 2,968,664 January 17, 1961 Arthur R. Sexton et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, lines 70 to 72 strike out "represents an olefin oxide such as ethylene oxide, l,2propylene oxide l 2-butylene oxide, 2,3-butylene oxide, or isobutylene oxide and wherein HSO HAm represents"; column 2, line 32, for "ethylen" read ethylene column 3, line 40, for "hours" read hour column 4, line 32, for tirethylamine" read triethyl amine column 8 line 9, for "2,204,443 read 2,204,433

Signed and sealed this 7th day of November 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer 7 Commissioner of Patents USCOMM-DC 

1. A METHOD OF MAKING FATTY ACID ESTERS OF HYDROXYALKANESULFONIC ACID AMINE SALTS WHICH COMPRISES MIXING APPROXIMATELY STOICHIOMETRIC AMOUNTS OF A FATTY ACID HALIDE HAVING FROM EIGHT TO TWENTY CARBON ATOMS AND A VIC-HYDROXYALKANESULFONIC ACID AMINE SALT WHEREIN THE VIC-HYDROXYALKANESULFONIC ACID HAS FROM TWO TO FOUR CARBON ATOMS AND THE AMINE HAS FROM ONE TO TWENTY CARBON ATOMS, BY ADDING THE FATTY ACID HALIDE TO THE VIC-HYDROXYALKANESULFONIC ACID AMINE SALT INCREMENTALLY AS REQUIRED BY THE ENSUING ESTERIFICATION REACTION AND HEATING THE RESULTING MIXTURE AT TEMPERATURES OF FROM 70* TO 135*C. UNDER AN ABSOLUTE PRESSURE NOT GREATER THAN 200 MM. OF MERCURY WHILE REMOVING THE EVOLVED HYDROGEN HALIDE AS FORMED FROM THE REACTION MIXTURE. 